Étude du traitement thermique à l’eau chaude en vue d’amélioration de la qualité des dattes sèches

Abstract

An experimental study of the rehydration, by hot water impregnation, of Deglet-Nour dates was made in order to improve the quality of dry dates. To this end several parameters of quality were simultaneously tested: moisture content, sugars, texture and color in order to allow a good appreciation of the final product. Various samples were rehydrated with 25, 45 and 65°C in solutions of ultrapure water sweetened to 0, 10 and 20 Brix. The obtained results highlighted a complementary maturation by hydrant and sugar inversion. The phenomenon of diffusion water-date was accelerated by the increase in the temperature of steeping but this one was slowed down by the increase in concentration of the sweetened solutions and the sugar losses in the steeping solution were negligible. Among several invested operating conditions, steeping with 30°C, during about eight hours, was selected as optimal treatment for a better quality of the final product. In order to restore the standard moisture content allowing a safe storage, a complementary drying operation can be proposed.